Test up to 5 subject and body variants right inside Gmail. Track opens, clicks, and replies. MailTrail declares the winner so you stop guessing.
Works with any Google Workspace account. No credit card. No sending limits from us.
Built for teams sending real email at
Features
Test different subject lines, opening lines, or full-body rewrites side by side without leaving your Gmail compose window.
Pixel-based opens, rewritten link tracking, and Gmail-history-based reply detection. We even flag Apple MPP proxy-inflated opens.
Two-proportion z-test on click-through rate. When results are significant, MailTrail auto-declares a winner.
Send the winning variant to everyone who didn't open, or export the list to your CRM.
Respect Gmail's daily limits with configurable per-hour throttling, automatic backoff, and retry on transient failures.
OAuth 2.0 with Google, RLS-scoped storage, HMAC-signed tracking URLs. Bring-your-own Google client for internal deployments.
How it works
Add MailTrail from the Chrome Web Store, connect your Gmail with a single click.
Hit the new A/B Test button in the compose toolbar. Add 2–5 variants and paste your recipient list.
We split recipients across variants, embed tracking, and send from your Gmail — throttled and safe.
Open the dashboard for real-time results, statistical confidence, and a one-click winner send.
Dashboard
Opens are inflated by mail apps now. We surface them, but MailTrail leads with clicks and replies — the signals real senders trust.
240 sent · running · 3d ago
Variant B lifts click-through by +111% vs control · p = 0.021
From the makers of Experimently
MailTrail is free by the team behind Experimently.ai. If email is just the start, try the full platform for landing-page experiments, personalization, and revenue optimization.
MailTrail is free forever. Install in 30 seconds and run your first test today.